1. Field of the Invention
The present invention relates generally to a pneumatic valve and, more specifically, to a lockout valve that controls fluid flow in a fluid system.
2. Description of the Related Art
Various types of fluid systems are known in the art that rely on the fluid flow of pressurized air. An example of a fluid system is a pneumatic system. These types of fluid systems periodically need maintenance, which requires careful control of the air flow supply to the system, as well as control of the air flow already within the system. Various types of valves are well known in the art for controlling the flow of fluid in a fluid system.
For example, a type of valve referred to as a lockout valve typically includes a slide mechanism that is positionable to control the fluid flow passing through the valve. The lockout valve provides for predetermined levels of flow, such as fully open, fully closed and an intermediate, partial flow, position. The slide mechanism is positioned in the open position when one hundred percent fluid flow is desirable. The slide mechanism is positioned in the closed position when zero percent fluid flow is desirable. The slide mechanism may be locked in this position using an external locking mechanism, such as a padlock, to prevent the unintended movement of the slide mechanism. The slide mechanism may be positioned in an intermediate, or bleed position, to provide partial flow through the valve. This position is advantageous when restricted flow is desirable until the pressure within the system equalizes. It should be appreciated that certain types of equipment may be damaged by rapid changes in air pressure.
One example of a lockout valve that provides for a gradual buildup of pressure across the valve in an open position to protect other components within the system, is disclosed in U.S. patent application Ser. No. 6,116,278 to Baumgardner et al., which is herein incorporated by reference. While the valve disclosed by Baumgardner et al. '278 works well, it utilizes a lever on the slide to maintain the position of the slide in an intermediate position, and does not provide for overriding of the intermediate position. Thus there is a need in the art for a lockout valve having an override mechanism that bypasses the intermediate position, to go directly from a closed valve to an open valve position to control the fluid flow therethrough.